EVALUATION OF IMPACT FORCE ACTING ON TSUNAMI SEAWALL DUE TO WATERBORNE DEBRIS

Abstract

 The existing estimation formula of tsunami waterborne debris impact force targets the collision force at the local point where the waterborne debris collides with the structure. On the other hand, in a plate-shaped structure such as a seawall, the deformation mode differs depending on the position where the waterborne debris collides, and the collision position is uncertain because the debris is floating on the moving water surface, so the impact force cannot be defined. In this study, for a tsunami seawall, a method to estimate the impact force based on the strain energy generated in the seawall structure was proposed. First, the applicability of the estimation formula under the condition of linear stiffness was validated by the in-air tests, and then a estimation method of the equivalent collision force of a plate-shaped structure based on strain energy was investigated by considering the collision period. In addition, from the results of the hydraulic experiments, it was shown that the impact collision force of a floating vessel can be evaluated by the existing estimation formula by using the above-mentioned evaluation method.